Bkook : Salmon Disease in the Eden. 



147 



miicli larger and fewer in number than the zoospores. They are not 

 released by the bursting of the sporange, as in the case of zoospores, 

 but escape by its decay. These resting spores . do not germinate at 

 once, but seem to fulfil the office of seeds proper, and remain over to 

 another season — at least those of Peronospora do, and it is likely 

 this species will develop similarly. Up to the present I have had no 

 resting spores germinate. 



It seems probable that the salmon fungus, and the fungus known 

 to pisciculturists as " byssus," are identical, or, at any rate, that both 

 belong to the same genus. 



In the Carlisle district the disease is generally regarded as pre- 

 senting a totally different appearance to anything seen before. Kelts, 

 they say, die every year after the spawning season, and are attacked 

 by a fungus, but this does not present the piebald appearance now 

 seen, nor is it so white in the water. At any rate, the disease is not 

 new here to fish in confinement — gold fish, gudgeon, and other fish 

 dying from a fungus which I find to be identical with that on salmon. 



After treating with a 10 per cent, carbolic acid solution, or a solution 

 of Tidman's sea salt in water sp. gr. 1*026, for several days, the circu- 

 lation of the granules in the filaments is still visible ; the growth of 

 the fungus appears arrested, however, but it is not clear that this is 

 the effect of the solution. 



In confinement, trout, ova, and avelins die of " byssus " from a 

 combination of several causes, the most important of which appears 

 to be the want of a sufficient supply of clean fresh water, and this 

 would point to the low state of the rivers during the present spring 

 as being, at any rate, a factor in causing the disease. Overcrowding 

 may have been another, as the fish were unusually plentiful duiing 

 the early spring ; but it appears difficult to entirely account for the 

 disease. 



EXPLANATION OF PLATE I. 



Fig. 1. — Various stages in the development of the filaments of Achlya. 

 {a) Fruit club nearly mature. 



Fig. 2. — Fruit club before formation of the spores. 



Fig. 3. — Fruit club after bursting. 



{a) Mass of spores. 



Cases after active zoospore has escaped. 



{c) Active zoospores. 



Fig. 4. — Development of zoospores. 

 Fig. 5. — Resting spore. 



Fernbrook, 



Huddersfield, April 18th. 



